DSLR stands for Digital Single Lens Reflex camera. These cameras are preferred over point-and-shoots for astrophotography
because of interchangeable lenses and the ability to change many of the settings (exposure, ISO, f ratio). When mounted to a scope
these cameras can rival CCD
cameras in image quality.
Mirrorless cameras (also known as CSC 'compact system cameras', EVIL 'electronic viewfinder, interchangable lens' & MILC 'mirrorless interchangeable lens camera') share the advantages of DSLRs and can be used in any of the ways a DSLR can for astrophography. For scopes
with limited back focus their shorter mount designs can be a significant advantage.